A US missionary being held in North Korea has been moved from hospital back to a labour camp, the US State Department said on Friday, citing Swedish diplomats who met the prisoner.
Kenneth Bae, 45, was reportedly moved on 20 January - the same day he made a public appeal for Washington to get him home.
The former tour guide and Christian missionary has been held in North Korea since being arrested in late 2012, when he was sentenced to 15 years of hard labour for unspecified hostile acts.
But last summer he was transferred to Friendship Hospital in Pyongyang, the North Korean capital, after losing 50 pounds (22 kilograms) his family said.
"The Department of State has learned that the DPRK transferred Mr Bae from a hospital to a labour camp, a development with which we are deeply concerned," State Department spokeswoman Jen Psaki said.
"We also remain gravely concerned about Mr Bae’s health, and we continue to urge DPRK (Democratic People's Republic of Korea) authorities to grant Mr Bae special amnesty and immediate release on humanitarian grounds," she said.
Psaki sad that Swedish Embassy representatives have met Bae 10 times since his detention, most recently at a labour camp on Friday.
"We continue to work actively to secure Mr Bae’s release," she said, adding that Washington remained prepared to send its human rights envoy for North Korea, Robert King, to Pyongyang for that purpose.
North Korea has so far rejected this offer and withdrew an invitation for King to visit Pyongyang last August.
The news coincided with an interview with Bae, which was published in Choson Sinbo, a pro-North Korea newspaper based in Japan. In it, Bae said that a Swedish Embassy official had visited him on Friday and told him that King would visit as early as Monday and by the end of the month at the latest.
The United States had originally offered to send civil rights activist Jessie Jackson out to North Korea, but the country instead approved the visit by King, Bae said in the interview. There were no further details about King or Jackson’s future plans.
A State Department official said Bae was moved back to the labour camp on 20 January.
His sister, Terri Chung, told Reuters Bae had been held in a labour camp from 14 May last year to 5 August, when he was moved to the hospital.
She said the family did not know where the camp was, except that it was far from Pyongyang and Bae was working eight hours a day, six days a week.
Chung also said her brother suffered from a variety of health issues, including diabetes, an enlarged heart, kidney stones and severe back pain.
Bae, a Korean-American, was last seen in public at Pyongyang Friendship Hospital on 20 January, when he appeared before reporters to ask Washington to secure his release.
It was his second media appearance since his arrest in 2012 and North Korea’s state KCNA news agency claimed that Bae himself had requested the news conference.
On Thursday President Barack Obama offered prayers for Bae.
"His family wants him home. And the United States will continue to do everything in our power to secure his release," he said.
On Tuesday, the last surviving members of the US Congress to have served in the Korean War sent a letter to North Korean leader Kim Jong-un, asking him to release Bae.
Additional reporting by Reuters